ROM Monitor Overview This chapter provides an overview of ROM Monitor concepts and operations. For instructions on how to perform various tasks in ROM Monitor (ROMMON) mode, see the other chapters in this book. This chapter includes the following main topics: • Information About ROM Monitor, page 1 • Entering ROM Monitor Mode, page 3 • ROM Monitor Commands, page 7 • Displaying the Configuration Register Setting, page 10 • Environment Variables, page 10 • Exiting ROM Monitor Mode, page 12 • Additional References, page 14 Information About ROM Monitor The ROM Monitor is a bootstrap program that initializes theXR 12000 hardware and boots the Cisco IOS XR software when you power on or reload a router. A version of the ROM Monitor software exists on each card and is factory supplied. The ROM Monitor program provides an initial power-on environment for each card. If the Cisco IOS XR software is rebooted or unable to run, the corresponding card returns to the ROM Monitor mode. When you connect a terminal to a card that is in the ROM Monitor mode, the ROM Monitor CLI prompt is displayed. Cisco XR 12000 Series Router Prompt rommon1> The ROM Monitor software is known by many names. It is sometimes called ROMMON because of the CLI prompt in ROM Monitor mode. The ROM Monitor software is also called the boot software, boot image, or boot helper. On the Cisco XR 12000 Series Routers, the Boothelper software is different from the ROM Monitor software, except for the Performance Route Processor-3 (PRP-3) cards. For PRP-3 cards, the boot helper is integrated with the ROM Monitor software. Cisco IOS XR ROM Monitor Configuration Guide for the Cisco XR 12000 Series Router, Release 4.3.x OL-28397-02 1 ROM Monitor Overview Information About ROM Monitor Although it is distributed with routers that use the Cisco IOS XR software, ROM Monitor is a separate program from the Cisco IOS XR software. During normal startup, the ROM Monitor initializes the cards, and then control passes to the Cisco IOS XR software. After the Cisco IOS XR software takes over, ROM Monitor is no longer in use. A copy of the ROM Monitor software exists on each card. If a card fails to boot the Cisco IOS XR software, the card is forced to run from the ROM Monitor mode. Because a card in ROM Monitor mode is not running the Cisco IOS XR software, that card becomes unavailable for normal router operations. Understanding the Role of the DSC The active Route Processor (RP) for the owner Secure Domain Router (SDR) is called the Designated Shelf Controller (DSC). This card performs system-wide functions, including the creation of additional non-owner SDRs. If the active DSC is placed in ROM Monitor mode, it is no longer running the Cisco IOS XR software. If a standby DSC is available, the standby RP resumes router operations. If a standby DSC is not available or is also placed in the ROM Monitor mode, then router operations stop. Designated Secure Domain Router Shelf Controller (DSDRSC) In addition to the DSC, each SDR in the system contains at least one DSDRSC. The DSDRSCs provide configuration and administrative functions for a single SDR only. The DSC also serves as the DSDRSC for the owner SDR. When the Designated Secure Domain Router Shelf Controller (DSDRSC) in an SDR is placed in ROM Monitor mode, the router operations are transferred to the standby DSDRSC (if available). If both the primary and standby DSDRSCs are in ROM Monitor mode, then the router operations cease because the Cisco IOS XR software is no longer running. Accessing ROM Monitor Mode on the DSC In most situations, you interact with the ROM Monitor mode only on the DSC (DSDRSC for the owner SDR). The DSC contains the administration configuration for the entire system and distributes the required software to all the other nodes in the router. All the tasks in this document describe ROM Monitor mode accessed through the DSC for the system. Note The only time you will interact with a non-DSC node is when reinstalling the Cisco IOS XR software on the standby PRP of a Cisco XR 12000 Series Router. Remember, the DSC is also the DSDRSC for the owner SDR. Environmental Variables and the Configuration Register Two primary connections exist between ROM Monitor and the Cisco IOS XR software: the ROM Monitor environment variables and the configuration register. The ROM Monitor environment variables define the location of the Cisco IOS XR software and describe how to load it. After ROM Monitor has initialized the card, it uses the environment variables to locate and load the Cisco IOS XR software. The common environment variables are BOOT, IP_ADDRESS, DEFAULT_GATEWAY, TFTP_FILE, TURBOBOOT and SUBNET_MASK. The configuration register is a software setting that controls how a card starts up. One of the primary uses of the configuration register is to control whether the card starts in ROM Monitor mode or Administration EXEC mode. The configuration register is set in either ROM Monitor mode or Administration EXEC mode as needed. Typically, you set the configuration register using the Cisco IOS XR software prompt on the active RP when Cisco IOS XR ROM Monitor Configuration Guide for the Cisco XR 12000 Series Router, Release 4.3.x 2 OL-28397-02 ROM Monitor Overview Entering ROM Monitor Mode you need to use ROM Monitor mode. When the maintenance in ROM Monitor mode is complete, you change the configuration register so the card reboots with the Cisco IOS XR software. Note Throughout this guide, the term PRP is used to refer to the PRP cards supported on Cisco XR 12000 Series Routers. Cisco XR 12000 Series Router supports both the PRP-2 and the PRP-3 cards. If a feature or an issue applies to only one platform, the accompanying text specifies the platform. Accessing ROM Monitor Mode with a Terminal Connection When an RP is in ROM Monitor mode, you can access the ROM Monitor software only from a terminal connected directly to the console port of the card. Because the Cisco IOS XR software (EXEC mode) is not operating, the nonmanagement interfaces (such as POS interfaces) are not accessible. Basically, all Cisco IOS XR software resources are unavailable. The hardware is there, but no configuration exists to make use of the hardware. Network Management Access and ROM Monitor Mode Some people get confused when they start to use ROM Monitor mode. It is important to remember that ROM Monitor mode is a router mode, not a mode within the Cisco IOS XR software. It is best to remember that ROM Monitor software and the Cisco IOS XR software are two separate programs that run on the same router. At any given time, the router is running one of these programs, but it never runs both at the same time. One area that can be confusing when using ROM Monitor and the Cisco IOS XR software is the area that defines the IP configuration for the Management Ethernet interface. Most router users get comfortable with configuring the Management Ethernet interface in the Cisco IOS XR software. When the router is in ROM Monitor mode, however, the router is not running the Cisco IOS XR software, so that Management Ethernet interface configuration is not available. To access other devices, such as a TFTP server, while in ROM Monitor mode on the Cisco XR 12000 Series Router, you must configure the ROM Monitor variables with IP access information. Entering ROM Monitor Mode The following sections describe two ways to enter ROM Monitor mode: Prerequisites Before you place a DSC in ROM Monitor mode, verify that the system is in a steady state: 1 Prepare the DSC: • Anticipate substantial downtime, including the loss of packet forwarding on the system. • Verify the sanity of the configuration file system using the cfs check command in EXEC mode. • Verify that all changes to the active router configuration are saved with the commit command in any configuration mode. • Verify that all changes to the active software set are saved with the install commit command in Administration EXEC mode. Cisco IOS XR ROM Monitor Configuration Guide for the Cisco XR 12000 Series Router, Release 4.3.x OL-28397-02 3 ROM Monitor Overview Resetting the Configuration Register and Reloading a DSC to ROM Monitor Mode • Verify that all install commit processes are complete with the show install committed command in Administration EXEC mode. This command displays the committed packages that become active during the next router boot. If any of the processes are not committed, use the install commit command in the Administration mode. 2 Verify that the other nodes in the system are in a steady state: • If a standby RP is installed, verify that it is in the ready state with the show redundancy command in EXEC mode. • Verify that all available nodes in the system are in IOS XR RUN state with the show platform command in EXEC mode. After you have verified that the system is in a stable state, you can enter ROM Monitor mode by setting the configuration register setting and entering the reload command, as described in the following steps: Resetting the Configuration Register and Reloading a DSC to ROM Monitor Mode In normal operating conditions, it should not be necessary to use ROM Monitor mode. If you do find it necessary to place a designated shelf controller (DSC) in ROM Monitor mode, make sure that the system is in a steady state and that you are prepared for the consequences of a system reload.